This invention relates to a protection device for electricity supplies.
Certain electrical devices, for example refrigerators, freezers, and air conditioning units, are highly susceptible to variations and transients in a mains voltage supply, particularly when the supply is interrupted and then restored. Such variations in the supply can damage the appliance, or shorten its working life.
There has previously been proposed an Automatic Voltage Regulator (AVR), which regulates a supply voltage to an appliance connected to the AVR if the supply voltage is within certain limits. An AVR, however, has disadvantages in that if the supply voltage passes outside the limits of the AVR, the appliance will remain connected and can still be damaged; also an automatic voltage regulator can be costly.